Heater Blower Motor

Heater Blower Motor

A heater blower motor is a major component of the climate control system of a vehicle. It is used for both heating and cooling purposes, forcing outside air through either the evaporator core or the heater core depending on the current needs. Most heater blower motors can be operated at different speeds, delivering just the right amount of air to the interior of a vehicle.

While the design of a heater blower motor doesn’t vary depending on a vehicle, the way it is controlled and operated can be different. Thus, older vehicles came with a manual operated heater blower motor with manual controls for the fan speed. By contrast, newer vehicles are equipped with a computer-controlled climate system, which doesn’t involve the driver in its operation. All you need is to set a desired temperature and let the system do the rest.

In case with manual operated air conditioning and heating systems, the heater blower motor circuit features a variable resistor which allows for changing the fan speed depending on the position of the manual controls on the dashboard. Fully automated climate control systems rely on signals from the control module and the data provided by the interior temperature sensor.

Whichever type of heater blower motors you have, its failure can cause a variety of problems with your climate control system. Here are some of them:

Lack of airflow through the vents

A faulty heater blower motor cannot create enough airflow to meet your heating or cooling needs. This is the main sign of a failing motor which should not be neglected if you want to drive with a high level of comfort.

Your heater blower motor runs with one or two speeds only

If you have a manually operated heater blower motor, it may not operate at all available speeds. This usually happens due to a failing switch or resistor.

Excessive vibrations and abnormal noises when the motor is running

Any squealing, grinding or rattling noises as well as excessive vibrations are indicators of a loose heater blower motor. They can be caused by a bad bearing, damaged impeller blades, fluid leaks and even dirt that blocks the fan. Whichever the cause, it must be addressed as soon as possible.

Smoke or smell from the dashboard’s vents

Major electrical problems may cause smoke or smell of burning plastic coming from the vents. If so, you should turn off your heater blower motor and stop the car. Get all your passengers out of the vehicle and open all windows to let the smoke escape from the cabin. Call your mechanic for a piece of advice.

The heater blower motors fuse fails frequently

A fuse is a maintenance item which is prone to wear. However, if it fails over and over again, you should check the heater blower motor and its electrical circuit.

You can’t turn off the fan

If you switch the control button to the off position, but the motor continues running, you should check the switch, relay and/or control module for signs of wear and damage.

Driving with a bad heater blower motor can make your driving uncomfortable in hot or cold weather conditions. Besides, frozen windows can also be a case, if the blower motor doesn’t perform its function.

Heater blower motor troubleshooting

Before replacing the heater blower motor, it must be properly diagnosed to find the root of the problem. In addition to a faulty motor you might also have a bad switch or a failed resistor. 

If the cause of the problem is a bad electrical part, it must be replaced with a new one to prevent further damage to the system. Once it is replaced, the entire system should be tested to make sure it functions properly.

Since your heater blower motor is a part of your vehicle’s electrical system, it should be diagnosed and replaced by a professional. Both diagnosis and replacement processes may involve specific equipment and require removing some of your dashboard parts or other components.